Behavioral models are useful tools in understanding how programs work. Although several inference approaches have been introduced to generate extended finite-state automatons from software execution traces, they suffer from accuracy, flexibility, and decidability issues. In this article, we apply a hybrid technique to use both reinforcement learning and stochastic modeling to generate an extended probabilistic finite state automaton from software traces. Our approach—ReHMM (Reinforcement learning-based Hidden Markov Modelling)—is able to address the problems of inflexibility and un-decidability reported in other state-of-the-art approaches. Experimental results indicate that ReHMM outperforms other inference algorithms.

Although many test case prioritization techniques exist, their performance is far from perfect. Hence, we propose a new fault-based test case prioritization technique to promote fault-revealing test cases inmodel-based testing(MBT) procedures. We seek to improve the fault detection rate—a measure of how fast a test suite is able to detect faults during testing—in scenarios such as regression testing. We propose an extended digraph model as the basis of this new technique. The model is realized using a novelreinforcement-learning(RL)- and hidden-Markov-model (HMM)-based technique which is able to prioritize test cases for regression testing objectives. We present a method to initialize and train an HMM based upon RL concepts applied to an application's digraph model. The model prioritizes test cases based upon forward probabilities, a new test case prioritization approach. In addition, we also propose an alternative approach to prioritizing test cases according to the amount of change they cause in applications. To evaluate the effectiveness of the proposed techniques, we perform experiments ongraphical user interface(GUI)-based applications and compare the results with state-of-the-art test case prioritization approaches. The experimental results show that the proposed technique is able to detect faults early within test runs.